The invention relates to improvements in methods of and in apparatus for making a stream of fibrous material, such as a stream of comminuted tobacco leaves. More particularly, the invention relates to improvements in methods of and in apparatus for making a stream which consists of a fibrous material (particularly tobacco) and is obtained as a result of a conversion of a flow of loosened fibrous material during transfer of fibrous material from a first path into a second path.
It is known to make a rod-like filler of tobacco or other fibrous material of the tobacco processing industry in a machine wherein a so-called distributor or hopper draws fibrous material from a source of supply to form a relatively wide flow of loose fibers. The flow is advanced along a first path, and its leader is transferred into a second path wherein the transferred fibrous material forms a continuous stream. The stream is thereupon trimmed to remove the surplus of fibrous material, and the thus obtained rod-like filler is draped into a web of cigarette paper or the like to form a continuous rod which can be subdivided into sections of unit length or multiple unit length, e.g., into plain cigarettes, cigars or cigarillos or into filter rod sections of desired length. Reference may be had, for example, to commonly owned U.S. Pat. No. 4,185,644 to Heitmann et al. and to commonly owned U.S. Pat. No. 4,564,027 to Heitmann. As a rule, fibrous material which leaves the first path is transferred to the underside of the lower reach of an endless foraminous belt conveyor to which the fibrous material is attracted by suction and which advances the stream past the surplus removing means, through a wrapping mechanism wherein the trimmed stream is converted into a continuous rod by draping it into a web of wrapping material, and thereupon through a so-called cutoff which severs the leader of the rod at regular intervals to convert the rod into a file of rod-shaped articles of desired length. The flow of fibrous material can be delivered in a direction transversely of the direction of advancement of the growing and fully grown stream along the second path.
A drawback of presently known apparatus for making a continuous stream of fibrous material is that they cannot prevent so-called stream stoppers, namely excessive accumulations of fibrous material in or downstream of the stream building or growing zone (e.g., at the surplus removing station), from appreciably influencing the output. Such accumulations entail a clogging of the channel for the conveyor which defines the second path and necessitate immediate stoppage of the entire machine or production line for an interval of time which is required to remove the stopper or stoppers prior to restarting of the machine or production line. Each stoppage of a cigarette rod making machine results in huge losses in output since a modern cigarette maker is designed to turn out up to 10,000 plain cigarettes per minute.